The present invention relates to a new and improved method of introducing oxygen into waters and to a container or vessel for the performance of such method.
With increasing chemical and bacteriological contamination of waters its content of dissolved oxygen decreases. This ultimately leads to imbalance of the equilibrium conditions between contamination and natural purification, so that the waters tend to so-to-speak "suffocate".
Due to excessive fertilization of the waters, for instance with chemicals such as phosphates, there is intensively promoted the growth of vegetation. The dying and decaying of such vegetation, on the other hand, leads to an increased oxygen consumption, until finally, particularly at the lower regions of the water, there is practically no longer available any oxygen.
During the summer months there thus occurs the so-called summer stagnation of the waters which continues up until the fall season and leads to the undesirable result that no natural water circulation takes place in such waters. There occurs a stratification or layering of the water. At the top of the body of water there is formed a relatively warm water layer of, for instance, a temperature above 15.degree. C. which extends over a height of about ten meters. This topmost layer of water still contains an adequate oxygen content. It is referred to commonly as the epilimnion. Below the epilimnion there is a layer of water which is referred to as the thermocline, which has a depth of between about ten meters to almost approximately seventeen meters. Within the thermocline the temperature of the water decreases from the upper region of such water layer towards the bottom region thereof until reaching a temperature of about 4.degree. C., and equally, the oxygen content is intensively reduced. Below the thermocline there is finally located a water layer which extends almost up to the bottom of the body of water, this water layer being referred as the hypolimnion. In the hypolimnion the temperature and the oxygen content which is too low is basically maintained, although slightly decreasing, even up to greater depths of such water layer up to almost forty meters. However, thereafter the oxygen content decreases suddenly, almost without any transition, up to null.
Thus it is particularly these deep water zones or regions where the dying and rotting vegetation particularly require to a great extent the oxygen, in order to render possible the natural purification or cleaning process of the waters.
Therefore, it has already been proposed to aerate these deeper situated water zones or regions in that water is upwardly conveyed from the base of the body of water, aerated and at the top of the body of water again allowed to flow-out. Yet, this aeration process causes upward conveying of the nutrients. Hence, the growth of the vegetation is promoted, which, in turn, leads to an increase in the dying-off products, so that finally oxygen is again consumed.
In order to reduce this effect, it has already been proposed that the upwardly conveyed ground water, following aeration, be returned below the thermocline, back into the upper regions of the hypolimnion. But this technique causes a certain disturbance in the stratification equilibrium or layering of the waters.
The circulation installations of both of the aforementioned processes are associated with considerable investment costs, are not particularly attractive in appearance and thus impair the landscape and also produce emissions in the form of noise and noxious odours. Even with the slightest amount of success such techniques require a great deal of energy.